Diodes Incorporated PI5C3257QEX

Overview

PI5C3257QEX from Diodes Incorporated is a quad 2:1 analog bus switch multiplexer/demultiplexer with three-state outputs, pinout- and function-compatible with 74F257/74ALS257 logic families. It features 5Ω on-resistance, near-zero propagation delay (0.25 ns), ultra-low quiescent current (0.2 µA typical), and operates over –40°C to +85°C ambient. Used for high-speed data routing in notebook and embedded bus architectures.

For engineers reviewing the PI5C3257QEX datasheet, PI5C3257QEX pinout, PI5C3257QEX application, or PI5C3257QEX equivalent, key selection criteria include on-resistance matching, enable/select timing (tPZH ≤ 4.8 ns), bus-switch isolation during disable, and QSOP-16 footprint compatibility with legacy 74-series logic layouts.

Technical Context

The PI5C3257QEX implements four independent bidirectional 2:1 analog switches controlled by a shared select (S) and enable (E) input. Each switch connects either IA/IB, IC/ID pair to YA/YB/YC/YD outputs with no DC path interruption-enabling direct bus coupling when enabled.

Its CMOS-based switch architecture delivers rail-to-rail signal handling (–0.5 V to +7.0 V), low charge injection (<1 pC), and minimal capacitive loading (CIN = 6 pF, CON = 14 pF). Propagation delay is dominated by RC time constant of RON and load capacitance-not internal logic-making it transparent to system-level timing budgets.

Key Specifications

Pinout & Package

PI5C3257QEX is packaged in a 16-pin QSOP (150-mil width), with 1.27 mm pitch and standard JEDEC MO-131 compliant footprint. Pin 1 is marked by a beveled corner or dot; pin 1 index area is located at top-left when notch faces up.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad 2:1 analog bus switch applications.

Compared with SN74CBT3257PW and 74LVC257PW, PI5C3257QEX delivers superior analog performance (5 Ω vs. 7 Ω RON, 0.2 µA vs. 10 µA ICC) and broader voltage tolerance (–0.5 V to +7.0 V), making it uniquely suited for mixed-signal, low-power, and legacy-interface bridging roles.

Availability

PI5C3257QEX is available at Aetrix Electronics and suitable for notebook memory bus switching, embedded microcontroller peripheral sharing, test equipment signal routing, and legacy logic interface bridging requiring stable component supply and long-term industrial availability.

Supply support for PI5C3257QEX includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The PI5C3257 belongs to Diodes' high-speed analog bus switch product line, engineered specifically for low-latency, low-distortion signal routing in portable computing, industrial control, and test instrumentation applications.

FAQ

What is the maximum continuous current rating per switch channel?

The PI5C3257QEX supports up to 120 mA DC output current per channel, verified under maximum ratings conditions. This rating applies to steady-state conduction with VCC = 5 V and ambient temperature ≤ +85°C. Derating is required above +85°C ambient or with elevated board temperatures due to thermal resistance limitations of the QSOP package.

Can PI5C3257QEX operate with 3.3 V logic levels while powered from 5 V?

Yes. The device accepts TTL- and CMOS-compatible input voltages (VIH ≥ 2.0 V, VIL ≤ 0.8 V) regardless of VCC, enabling 3.3 V control signals on a 5 V supply. All inputs and outputs tolerate –0.5 V to +7.0 V, supporting mixed-voltage system integration without external level shifters.

Is the PI5C3257QEX pinout identical to the 74F257 in all packages?

Yes-the PI5C3257QEX is functionally and pinout-compatible with 74F257, 74ALS257, and 74AS257 across QSOP (Q), TSSOP (L), and UQFN (ZHD) packages. Pin assignments match exactly, including shared S, E, and I/Y signal positions, enabling drop-in replacement in existing 74-series logic layouts.

Does the device require external pull-up or pull-down resistors on control inputs?

No. The PI5C3257QEX has internal input hysteresis (150 mV) and guaranteed VIH/VIL thresholds, eliminating need for external biasing. Inputs are TTL-compatible and fully specified from –40°C to +85°C; however, for noise-prone environments, a 10 kΩ pull-down on E is recommended to ensure defined startup state.